1. Field of the Invention
The present invention relates generally to solid-phase immunosubstrates for use in immunological assaying and more particularly to a surface coating or film for application to a solid-phase surface and to the immunosubstrate formed by the utilization of the surface coating.
2. Description of the Prior Art
Many solid-phase surfaces are presently employed in immunological testing to which a protein, such as an antibody (specific immunoglobulin) or an antigen (any one of many protein or protein bound substances), may be adsorbed to form an immunosubstrate. The solid-phase may be a metallic surface, such as is employed in polarization change studies, or a glass or smooth plastic surface in which the protein is fixed onto the surface by air drying, heat denaturation or the use of organic fixing agents such as acetone, ethanol, methanol or formaldehyde. In some cases use is made of protein adherence to the polymer chains of certain plastics without a fixing process, such as in the adsorption of viral, bacterial, hormonal or other antigens to polypropylene and/or polystyrene test tube walls, beads or microtiter plates. Cellulose and cellulose derivatives, such as mixtures of cellulose acetates and cellulose nitrates, have also been utilized as adsorptive surfaces for protein binding.
These prior art solid-phase surfaces are generally utilized without any surface coatings to alter the adsorptive character of the surface. A common problem with such surfaces is that care must be taken when washing the surface during test procedures to prevent the immunoreagents or analytes that have adhered to the surface from being removed therefrom. Additionally, the use of an uncoated surface limits the user to the surface area of that surface for immunoreagent adsorption, whereas an immunoadsorptive coating on the surface has a thickness which creates an immunoreagent adsorptive volume, thus permitting the adsorption of a greater quantity of immunoreagent and increasing the sensitivity of the assay.
The surface coating or film of the present invention is applied to solid-phase surfaces to increase adsorption and retention of immunoreagents. Its main constituent is a water based emulsion of microdiameter size polymer beads to which may be added a material which imparts light scattering centers into the coating. No prior art is known to the inventors that utilizes such polymer beads within a surface coating for solid-phase surfaces, nor that combines them with a material providing optical properties that improves the fluorescent testing capability of the immunosubstrate formed through the use of the surface coating.